Black silicon solar tech comes of age

Pete Danko EARTHTECHLING, 25th December 2011

Black silicon has been bubbling in the background of solar research and development the past couple of years, hinting at a way to drive down the cost of solar power, but has yet to bust out.

But change could be afoot. The National Renewable Energy Laboratory (NREL) has licensed its patented black silicon technology to New Jersey-based Natcore for the development of a line of products.

Before we go on, we should probably explain what black silicon is. For that, we borrow some well-chosen words from Natcore: "Black silicon refers to the apparent color of the surface of a silicon wafer after it has been etched with nano-scale pores; the black color results from the absence of reflected light from the porous wafer surface."

The are several benefits that flow from this manipulation of the wafers. First, the NREL estimates that it reduces cell processing costs by 4 to 8 percent.

Efficiencies at peak solar exposure are a little lower, but "the black silicon prevents reflection of low-angle morning and afternoon sunlight far better, which means a jump in photovoltaic efficiency of at least 1 percentage point can be achieved." So in that end, the lab says, that means overall savings in solar cell manufacturing of 1 to 3 percent.

"This technology will play an important role in moving forward the availability of solar technologies," William Farris, NREL vice president for Commercialization & Technology Transfer, said in a statement.

"It is one more step to help bolster the Department of Energy's SunShot Initiative to make solar energy cost competitive with other forms of energy by the end of the decade."

Natcore said the black silicon technology NREL developed will be particularly effective when combined with its own proprietary process to "passivate" the increased area of exposed silicon that results from boosting the light absorption of the cells.

"The combined NREL-Natcore technologies will reduce cost by eliminating the need for thermal oxidation," Natcore President and CEO Chuck Provini said in a statement.

"And they'll increase output by enabling cells to be more productive throughout all daylight hours."